1. Field of the Invention
The present invention relates to methods and devices for assaying biological fluid samples. More particularly the invention relates to methods and devices for detecting analytes, such as drugs, in urine.
2. History of the Related Art
In their most simple form, chromatographic analyte devices permit an assay to be performed in a single step (application of an analyte sample to the device) to producer visually observable assay results (such as those indicated by colored bars on the test strip). However a common limitation of such devices is that they can only be used to detect a single analyte, requiring that serial assay procedures be performed to detect additional analytes (for example to test a sample for the presence of a panel of narcotics). Multiple dipping steps such as are commonly used when multiple dipstick assays are separately performed, present not only possible loss of sensitivity of the assay (through reagent mixing or possible loss reagent solutions) but also an esthetic and hygienic problem for the analyst. Repetitive performance of assay procedures is also tedious, which increases the risk that assays will be performed improperly or the results misinterpreted.